| 摘要 |
The invention relates to a multiwall paper bag that represents an improveme nt in the field of bags for carrying bulk material, especially particulate or powdered material. The bag has an inner ply of a high performance kraft paper, an intermediate layer or ply of a thin polyethylene secured to the outer surface of the inne r ply, and an outer ply of high performance kraft paper that is secured to the intermediat e ply. At least one end of the bag is closed during initial formation of the bag. The other end can be left open for filling and subsequent closing, or it can be initially clos ed and provided with a filling valve. At least the intermediate ply, and preferably the inne r ply as well, is microperforated for venting of air during filling. The intermediate ply i s secured to the inner ply either by a plurality of longitudinally extending transversely space apart lines of adhesive or the securing adhesive is spread completely over the mating surfaces of the two plies.
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